1. Field of the Invention
The present invention relates to a seat sliding apparatus for vehicles.
2. Description of the Prior Art
A conventional seat sliding apparatus for vehicles is disclosed in Japanese utility model laid-open publication No. 61(1986)-138729, which was published without examination on Aug. 28, 1986. The conventional seat sliding apparatus includes a pair of laterally spaced lower rails which are fixedly secured to a vehicle body and a pair of laterally spaced upper rails slidably mounted on the lower rails for supporting a seat-cushion thereon. In detail, each of the lower rails has a substantially U-shaped cross-section and each of upper rails has a substantially inverted U-shaped cross-section. A roller is disposed between a central portion of each upper rail and a central portion of each lower rail. Each distal end of the upper rail is bent through approximately 90 degrees inwardly in the lateral direction and is formed into a lower projection. Each distal end of the lower rail is bent through approximately 90 degrees outwardly in the lateral direction and is formed into an upper projection, which is positioned above the lower projection. A set of balls is disposed between the upper and the lower projections. Since two upper projections are provided on the lower rail and two lower projections are provided on the upper rail to sets of balls are provided with the combination of the upper and lower rails. A unit is employed which accommodates the rollers and the sets of balls for unitary movement thereof.
In the conventional seat sliding apparatus, a belt-anchor-bracket is secured to one of the upper rails and a distal end of a seat-belt is detachably connected to the belt-anchor-bracket. In the case where the seat-belt is tensioned during collision of the vehicle, an unexpected strong force is applied to the upper rail in the upward direction. Since the lower projection of the upper rail is in the form of a cantilever configuration, the lower projection may be disengaged from the set of balls due to resulting force. This results in the separation of the upper rail from the lower rai1.